Fire Risk Analysis for Nuclear Power Plants: Methodological Developments and Applications

A methodology to quantify the risk from fires in nuclear power plants is described. This methodology combines engineering judgment, statistical evidence, fire phenomenology, and plant system analysis. It can be divided into two major parts: (1) fire scenario identification and quantification, and (2) analysis of the impact on plant safety. This article primarily concentrates on the first part. Statistical analysis of fire occurrence data is used to establish the likelihood of ignition. The temporal behaviors of the two competing phenomena, fire propagation and fire detection and suppression, are studied and their characteristic times are compared. Severity measures are used to further specialize the frequency of the fire scenario. The methodology is applied to a switchgear room of a nuclear power plant.     

Comparative Fire Risk Study of PCB Transformers

A risk assessment comparing the acute effects of mineral oil and PCB-askarel dielectric fluids in two transformer sites was performed. The first site has the installation characteristics for a PCB-askarel-filled transformer with sprinkler fire protection. A risk comparison is made between two types of transformers (PCB-askarel-filled and mineral oil-filled) for this site. The second site (a vault) has the installation characteristics for a mineral oil-filled transformer, and a risk comparison is made in a fashion similar to the first site. Risk is expressed in terms of frequencies of one or more acute injuries or fatalities per transformer year.